To sleep, perchance to dream

People have always attempted to interpret dreams, from the biblical Joseph to the celebrated Viennese psychologist and psychoanalist Sigmund Freud (1865-1939). Freud’s theories were based on the concept that memories, and especially deep memories, with their significant elements represented symbolically or in some other coded form, are the substance of dreams. For this reason, he maintained, the interpretation of dreams can be a key to a person’s subconscious mind, and so make an important contribution towards understanding and resolving neuroses. Modern evidence suggests that dreaming and REM sleep resemble what has been described as ‘sorting the day’s events into the filing cabinets of the mind’. The evidence for this comes from the enormous amount of work on humans and animals in so-called sleep laboratories, and from simple observations of our own behaviour. For example, most people find they need more sleep when they change jobs or when they have an increased workload demanding a good deal of mental effort. When they are stressed in this way there is an increased desire for sleep (although that sleep may not come easily, because of anxieties). When life is relatively trouble-free, most people find they do not need as much sleep..Babies and children, who are coming to terms with the world and learning vast amounts every day, for similar reasons have an especially great need for sleep and, because of the great mental workload a child has in learning about the world around, it seems to follow logically that children need considerably more REM sleep than do adults.

In the laboratory, animals have taken part in experiments in which they have to learn in order to receive rewards of food. They show an increase in REM sleep in the period following the learning activity, although if the experimental task is not learned there is no increase in REM sleep. There is also an increase in the level of protein synthesis in the brain during REM sleep, making the synthesis greater than in the wakeful state. Many scientists have postulated that memor- ies may be somehow encoded in protein molecules or in electrical pathways between neurons, and some have therefore suggested that dream sleep’s purpose, with its high levels of electrical activity and chemical synthesis, is concerned with memory restoration and consolidation.

But this does not really explain the significance of dreams. Few people report their dreams as logical sequences – usually one says ‘I had a very strange dream last night’. Although the mechanisms Freud postulated for dreaming may be wrong, his theory that memories are involved may prove to be along the right lines after all.

REM sleep is also viewed by some as a means of resolving the conflicts of the previous day or days and possibly providing a rehearsal for behaviour we have yet to carry out. But not all dreaming is necessarily involved in resolving psychic tensions. There are many examples of inventors, scientists, artists and writers deriving creative inspiration from their dreams. The German chemist F. A. Kekule von Stra-donitz (1829-1896), who discovered the ringed chemical structure of benzene, was reported to have dreamed of snakes lying end-toend in a circle. The American Elias Howe (1819-1867), the inventor of the sewing machine, was said to have dreamed of spears with hollow tips before he created his remarkable machine. Dreams can also be created in an instant to ‘make sense’ of an external stimulus such as a loud noise. In the second or two between hearing the noise and waking up we appear to dream for many minutes and incorporate the noise into a dream story.

Do we need to dream?

There is little doubt that dreaming and REM sleep are essential for normal healthy minds. People woken during REM sleep show increasing levels of irritability and fatigue. In certain pathological conditions the degree of REM sleep is diminished. In clinical de-pression, for example, in which patients have diffi-culty sleeping at all, the time spent in dream sleep is diminished. Manic-depressives, who show extremes of elation and depression, are extremely short sleepers compared to normal people and they have a very limited period of dream sleep during the manic phase. Interestingly, psychotherapists report that while the patient is manic it is impossible to make him or her understand new ideas. This may be because the patient is experiencing far less dream sleep than a normal person and therefore the brain is physiologi-cally incapable of creating the new neurological links necessary for assimilating new information. Small amounts of dream sleep are also found in the senile, the mentally handicapped and aphasic patients. None of these groups is doing much learning and therefore the individuals are not establishing new patterns of cerebral activity in the processes that may be manifest as dream sleep.